.TH std::experimental::ranges::SizedSentinel 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::experimental::ranges::SizedSentinel \- std::experimental::ranges::SizedSentinel

.SH Synopsis
   Defined in header <experimental/ranges/iterator>
   template< class S, class I >

   concept bool SizedSentinel =
       Sentinel<S, I> &&
       !ranges::disable_sized_sentinel<std::remove_cv_t<S>,
   std::remove_cv_t<I>> &&                                              \fB(1)\fP (ranges TS)
       requires(const I& i, const S& s) {
           { s - i } -> Same<ranges::difference_type_t<I>>&&;
           { i - s } -> Same<ranges::difference_type_t<I>>&&;

       };
   template< class S, class I >                                         \fB(1)\fP (ranges TS)
   constexpr bool disable_sized_sentinel = false;

   The SizedSentinel concept specifies that an object of the iterator type I and an
   object of the sentinel type S can be subtracted to compute the distance between them
   in constant time.

   Let i be an iterator of type I, and s a sentinel of type S such that [i, s) denotes
   a range. Let N be the smallest number of applications of ++i necessary to make
   bool(i == s) be true. Then SizedSentinel<S, I> is satisfied only if:

     * If N is representable by ranges::difference_type_t<I>, then s - i is
       well-defined and equals N; and
     * If -N is representable by ranges::difference_type_t<I>, then i - s is
       well-defined and equals -N.

   The variable template disable_sized_sentinel provides a mechanism for iterators and
   sentinels that can be subtracted but do not meet the semantic requirements of
   SizedSentinel to opt out of the concept by specializing the variable template to
   have the value true.

   Equality preservation

   An expression is equality preserving if it results in equal outputs given equal
   inputs.

     * The inputs to an expression consist of its operands.
     * The outputs of an expression consist of its result and all operands modified by
       the expression (if any).

   Every expression required to be equality preserving is further required to be
   stable: two evaluations of such an expression with the same input objects must have
   equal outputs absent any explicit intervening modification of those input objects.

   Unless noted otherwise, every expression used in a requires-expression is required
   to be equality preserving and stable, and the evaluation of the expression may only
   modify its non-constant operands. Operands that are constant must not be modified.

   Implicit expression variations

   A requires-expression that uses an expression that is non-modifying for some
   constant lvalue operand also implicitly requires additional variations of that
   expression that accept a non-constant lvalue or (possibly constant) rvalue for the
   given operand unless such an expression variation is explicitly required with
   differing semantics. These implicit expression variations must meet the same
   semantic requirements of the declared expression. The extent to which an
   implementation validates the syntax of the variations is unspecified.
